Former Manchester United star Danny Welbeck haunts Old Trafford
Manchester United 1 - 2 Arsenal
The brutal assessment Louis van Gaal offered of Danny Welbeck last September was that he lacked the requisite talent. And by the former standards of Manchester United that was most certainly right.
His strike-rate for his home-town club was almost one every five games and the misses were typified by the shot he lifted straight into the arms of Bayern Munich's Manuel Neuer, as the light was extinguished on the club's Champions League status last year.
But the problem for the Dutch manager who is about to preside over a second successive United season minus trophies for the first time since 1989 is that those United standards no longer apply.
The irony of Welbeck scoring the goal which eliminated his old side from the FA Cup is that he offered something that they have lacked all season. Pace, penetration at the top of the team, something to force defences back and create the space for a midfield to kill them as United's always did.
He latched onto a loose Antonia Valencia backpass, beating David de Gea to the ball, and coolly finished into the open net.
United's knowledgeable fanbase applauded Welbeck off in the 72nd minute, by which time he had taken the Arsenal acclaim too.
It was only four minutes later that the fragile edifice United have so lavishly assembled creaked a little more. Angel di Maria was dismissed for diving and grabbing at the referee.
It was destined to become the post-match soundtrack but it should not disguise the fact that Arsenal were worthy winners.
Even the fabric of Van Gaal's programme notes told of a United side struggling for an identity they put down somewhere and cannot quite locate.
"We are all human beings and we all have bad days," he wrote. It was not exactly blood and thunder talk; no real sense that this team were going to make a night of it - not even against an Arsenal outfit who are such a pale imitation of the side that collided with United like a force of nature a decade ago.
Wenger's side went at it hardest in the first half, though. Though Hector Bellerin was sorely tested early on by the wide player who is doing what we expected from Di Maria - it was Ashley Young running at full-backs - Wenger's players were the ones with a plan. Nothing titanic from them: sit, allow United possession and strike on the counter-attack.
But the regularity with which Van Gaal's side passed up easy possession made it a serviceable approach.
Alex Oxlade-Chamberlain, the most dangerous player of the first half, made it work, with wi th to operate on the right. He had already clipped narrowly over the bar when he took on Mesut Özil's measured ball in the 25th minute and embarked on a giddying slalom across the edge of United's area, beyond Young, Daley Blind and Chris Smalling.
He slid the ball left to Nacho Monreal to stroke home an opening goal: his second for Arsenal.
It was a catalyst for United to find some kind of life. One of their strategies - diagonal crosses to Marouane Fellaini - wasn't quite what we had always anticipated from the court of King Louis with Per Mertesacker (pictured) up to the challenge. The sight of Di Maria running at Monreal seemed a more promising way to exploit Arsenal's defence. It didn't happen.
As it was, Wayne Rooney was the one jockeying for space when Di Maria delivered from the right four minutes after United had fallen behind. He had been in Laurent Koscielny's line of vision but Rooney's movement was as exquisite as his headed finish.
Van Gaal's sense of discontentment was clear with two half-time substitutions - most significantly Michael Carrick for Ander Herrera, who had been struggling with Santi Cazorla - but Arsenal continued to threaten.
United dived into their opposition with a regularity which highlighted their struggle. Adnan Januzaj arrived but then, within minutes, Di Maria was gone - booked for diving and then dismissed after grabbing referee Michael Oliver's shirt in frustration.
There was more indignation when Januzaj went down as the chasing Monreal followed him into the box in a dive which was also theatrical. Even then, there were more chances for Arsenal. Alexis Sanchez sent a ball skimming across the area at the death.
For Wenger, joy. For Van Gaal, a sense of where things can possibly pick up from here.
Manchester United: De Gea, Valencia, Smalling, Rojo (Januzaj 73), Shaw (Jones 46), Blind, Di Maria, Ander Herrera (Carrick 46), Fellaini,Young, Rooney. Subs: Da Silva, Mata, Falcao,Valdes.
Sent off: Di Maria 77
Booked: Ander Herrera, Fellaini, Young, Rojo, Di Maria, Januzaj.
Goal: Rooney 29
Arsenal: Szczesny, Bellerin (Chambers 66), Mertesacker, Koscielny, Monreal, Coquelin, Cazorla,Oxlade-Chamberlain (Ramsey 51), Ozil, Sanchez, Welbeck (Giroud 74). Subs: Gibbs, Walcott, Martinez, Akpom.
Booked: Bellerin, Ramsey
Goals: Monreal 25, Welbeck 61.
Man of the match: Coquelin
Match rating: 7/10
Referee: Michael Oliver (Northumberland)
Attendance: 74, 285